Ehop

i am going to be putting a system into my car soon but i have a question.

ya know how amps ar rated their watt's at a certain ohms(300W @ 2ohms/150W @ 4ohms), well what determines those ohms? is it the sub?

the sub i am looking at is 300watts(RMS) @ 4ohms. so would i need to look for an amp that makes an RMS wattage of 600W @ 2 ohms and 300W @ 4 ohms? or is the resistance something i can adjust on the amp?


Modified by Ehop at 4:07 PM 1/18/2008

Ehop

also how would i choose a capacitor. i know they are rated in Farad's and a farad is the storage capacity, but is there a formula for farads to amps?

Bob Dole!

You'd probably get a whole boatload more responses in the Audio/Security section.

Ehop

yea it got moved there, i hadnt come online in a while n didnt think much when i posted

Ehop

bump... anybody got the answers?

fcm

The speaker, [sub] determines the load, [ohms], speaker VC, [voice coils] have resistance, [impedance] measured in Ohms.

The sub you are looking at is a 300W "continuous", [also called RMS] 4 ohm sub, [it has a 4 ohm VC] you will want to find a mono block sub amp that is rated at 1x300W RMS into 4 ohms, if the amp does not have a "regulated power supply" the same amp would make 1x600W RMS into 2 ohms and 1x1200W RMS into 1 ohm. [if the amp was "stable" with a 1 ohm load connected to it]. 94

sqsi

Don't wast you money on a capacitor, you don't need one

Ehop

if im reading what ur saying then my assumption was right, right?

i want an amp that can produce 300 watts at 4 ohms, to match my sub(300 watts[rms] with 4 ohms of internal resistance).

some capacitors are very cheap though, why do u say they are not worth the money?

fcm

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Ehop &raquo;</TD></TR><TR><TD CLASS="quote">if im reading what ur saying then my assumption was right, right?

i want an amp that can produce 300 watts at 4 ohms, to match my sub(300 watts[rms] with 4 ohms of internal resistance).</TD></TR></TABLE> That is correct, although a 350W-400W amp would be better, even a 500W amp, it is better to be over powered, your speaker is 300W continuous so it will be 600W peak/max power.

A 300W amp will do the job, having an amp with a little more wattage will give you "dynamic head room" so when you crank up the volume you do not drive the amp into clipping, [distortion] and the bass will stay "clean" even when loud.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Ehop &raquo;</TD></TR><TR><TD CLASS="quote">some capacitors are very cheap though, why do u say they are not worth the money?</TD></TR></TABLE> A cap has a use in an audio system, it is not a wast of money if it is used as intended, it is unlikely that you would need one with a 300W amp, but if after you install the system, and assuming it is done properly, and you find you have dimming problems, [dash/head lights or the HU lights] when you crank up the volume and the bass "hits", or the vocals get a little distorted as the bass "hits", then a cap is the least expensive way to deal with it.
The reason the lights dim is because there is a lack of current, the alt. can not produce enough current, [amps] that the car needs, [lights] and what the audio system, [sub amp] needs, when the amp is working it's hardest, a lot of things happen when more current is needed then the alt. can supply, the most noticeable is the dimming, to the beat of the bass, lights, it is also hard on the alt. and the amp and speakers, [sub].
The proper fix is to upgrade the alt. to a bigger one, [more current, [amps] output] but because the current draw is intermittent, [only when volume is cranked and bass is hitting] a cap, [no more then 1 farad on your system] installed at the sub amp can supply the amp with the current it needs.
Keep in mind, a cap is also a load on the alt. just like the amp, so before you install on, make sure you need it, have your alt. load tested to make sure it is working properly. 94